It All Started With Red Boxers
by PotatoLemonTart
Summary: Gumball and Marshall haven't been very fond of eachother since the Ash incident. But a pair of Red Boxers changes their relationship completely. Rated M.
1. Chapter 1: The Incident

"Doop-da-doo, dum-da-dum-dum..." Gumball sang while taking a shower in Fionna and Cake's house. He had been taking a vacation at their house, to take a break from the stress and restlessness of his princely duties.

"Hey, PG! You almost done in there?" Cake said through the door.

"Yeah, just a bit!" He replied, turning the shower knob to the right.

"Okay, hurry up then! You're gonna miss out on Bacon-Pancakes!" Cake walked away humming the Bacon-Pancake song.

Gumball opened the shower curtains and walked out if the tub, then dried off his gummy hair with a towel, and dried the rest of his body. He opened his pink duffel bag, pulled out some red boxers, and put them on.

 _Hmm... These feel okay._ He thought to himself, in front of a mirror as he turned his body. _It kind of exaggerates my butt though._ He reached in his duffel bag again for a white button-up shirt, with a baby-blue collar. He put that on and examined how he looked in them as well.

"Hey Fionna, I know your in the middle of planning how your gonna kiss Gumball, but I need something red..." Marshall Lee just walked in casually.

"MARSHALL!" Gumball quickly pulled the shower curtain to cover up his body. "What are you doing here?!" His face faded to a hot pink.

Marshall Lee barely even look surprised. "Oh. It's you... Well, I just need something red." Marshall Lee asked. Gumball stopped think for a moment. _Oh glob... I'm wearing red boxers. I cannot let him see them under any circumstance._ Gumball knows from experience, that Marshall Lee would devour anything red.

Gumball was very worried. What if he saw them? "Well, e-excuse me, b-but I think you should knock before you enter a b-bathroom!" Gumball was both embarrassed and annoyed.

"Oh, were are my manners?" He bowed down, "I am so sorry I have disturbed you, my highness." Marshall Lee said mockingly. The Vampire King laughed. "Seriously, do have anything red? I haven't had anything for days."

Gumball knew he was just messing around, but that really pushed his buttons. "Really? Are you just going to shrug off the fact that you could of saw me stark-naked?!" He let go of the curtain and started to rant about how rude and ignorant Marshall Lee was. Soon, he realized that Marshall Lee was staring at him oddly.

Gumball realized that his red boxers were in the wide open, and of all times, he happened to have an erection, which was very visible.

Gumball, who is now shaking, decided to try and compromise. "Marshall Lee, we can just go and get some fruit from inside. You don't have to-" Marshall Lee pushed him to the wall before Gumball had a chance to finish speaking. Gumball yelped, and Marshall Lee smirked.

"Sorry Gumball, I'm just very... **Thirsty.** " He said very sexually. Gumball was about to protest, but the vampire had grabbed the bulge in his boxers. "And it seems you are too..."

Gumball's face had turned to crimson. "M-marshall Lee... Please d-don't do this..." Gumball pleaded. Marshall Lee completely ignored him, and he got closer and closer to his face. He was about to press his lips against Gumball's, when he came up with something better. He slowly got lower until his face was near the bulge Gumball's boxers. He licked at it first, and Gumball groaned.

"M-marshall... s-stop..." He pleaded again.

"Stop? Why would I do that? You're obviously enjoying this." He came back up to his face. "Io need your sugar." Gumball shivered. He had never seen Marshall Lee act like this.

"Bacon-Pancake attack!" Cake barged in and threw the Bacon-Pancake at Marshal Lee and it hit the side of his head. "PG, are you okay? I heard you yell and..." She came to realize they had been doing, and threw the pan away.

"Cake, I promise this is not what it looks like." Gumball pushed Marshal Lee away.

"U-Uh... I didn't do that." She said nervously. Gumball quickly ran to the door and shut it and started freaking out. "Marshall Lee! Why did you do that?! You could of given Cake the wrong idea and..." He started to rant to himself again. But, Marshall Lee just stared at his boxers again. With the Bacon-Pancake still stuck to his head. "Oh, for the glob's sake!" Gumball had walked over to Marshal Lee and pressed his thumb down on his pressure point, which was on his shoulder. This snapped Marshal Lee back to his normal self. He then grabbed the pancake and threw it out the window.

"Finally! As I was saying..." Gumball started mumbling to himself, again. Marshall Lee yawned and looked at his wrist. He waited for a bit, then brought up food again.

"Well, I should go have some breakfast. You wanna come?" He said.

"Are you...? Ugh! ...Fine." Gumball had given up on trying to lecture The Vampire King. Gumball had put one some pink jeans, and walked with Marshall Lee to the main room of the tree house. Fionna had woken up and waited at the table.

"Yo, PG! Are you okay? I heard Cake had to help you." Fionna said. Cake looked over at them. She pretended to zip her mouth.

"Oh, well this guy over here, just gave me a little fright." Gumball patted Marshall Lee's back, hard. He was very mad at Marshall Lee, who rolled his eyes, and slid in on the long seat with Fionna.

"So, Fi. I see you weren't 'practicing' this morning?" He smirked. Fionna knew what he was talking about.

"N-no! I told you, I don't do that anymore!" Fionna said nervously.

"You don't do what, anymore?" Gumball inquired.

"It's nothing!" She pointed at Cake. "Hey look, Cake's done!" Fionna tried to get off the topic.

"Bacon-Pancake for you, Bacon-Pancake for you, Bacon-Pancake for me, and red fruits for you!" Cake said, as if she were working at a pancake house. "Everyone dig in!"

Fionna grabbed the syrup bottle and squeezed it. Nothing came out. She tried again, but the cap flew off. All of the syrup squirted on to her pajamas. "Aw, butts. I'm gonna go change." Fionna stuck her arms out and walked to the bathroom.

Now it was just Gumball, Cake, and Marshall Lee. It was completely silent. Cake sat in front of Gumball, and they just stared at each other, awkwardly. Gumball couldn't help but blush.

Marshall Lee stuck his fangs in a strawberry, and sucked the red color out of it. "Hmm... This doesn't taste as good as Gumball..." Cake and Gumball looked at him in shock. Did he really just say that?

Gumball decided to just end his vacation right then and there. He wasn't comfortable with the situation at all. "Well, I think it's about time for me to go back to the Candy Kingdom. Cake, please tell Fionna I had an amazing time, and forget about anything that happened today." Gumball went to grab his duffel bag and went down the ladders to get out of the house. He called Monochromicorn and got on him, then took of into the air.

Monochromicorn noticed that Gumball was pensive. "Prince Gumball, is something bothering you?" Monochromicorn said to him in Korean.

"What? Of course not... It's nothing, I'm fine." Gumball's face warmed and faded into a hot pink.

"Sir, your blushing."

"N-no I'm not. I'm just... frustrated with someone at the moment."

"Okay, whatever you say, prince."

* * *

It was about 8:30 now. Gumball would've been asleep by now, but he couldn't fall asleep. Whenever he lied in bed, he thought about the Red Boxers. He looked over at it for the 10th time. Trying it on once wouldn't hurt, right? He took the Red Boxers from a drawer, and changed into it. It still felt warm from earlier in the day. He looked at the mirror. _This actually feels comfortable... I should wear these more often._

He kept on observing, then he heard the door creak open. He looked over at the door. It was slightly opened. It's probably just the wind. He looked back at the mirror, and sighed.

"Damn, those boxers really make your ass look good..." Gumball tensed up. He looked behind him and there he was. The Vampire King.


	2. Chapter 2: Caught Again

"I see you are wearing those red boxers again?" Marshall Lee said smugly.

There was nothing near Gumball that can cover him up, so he tried using his arms. As you can imagine, that didn't really work.

"What are you doing here?!" Gumball yelled at him. This was the second time he had done this.

"Why should we worry about that? All that matters, is that I get under your boxers..." He smirked.

"Th-that's not happening." Gumball said, trying to look stone faced.

"Aww, C'mon. Let me put it this way," Marshall Lee floated over to him, and moved him to face the mirror. "Wouldn't you want to date you? I know I defiantly would." He had tried to get Gumball aroused, and he grabbed his bulge.

"N-no! I'm n-not letting this happen again!" He pushed Marshall Lee away.

"It looks like we're gonna have to do this the hard way..." Marshall Lee pushed Gumball to the wall. Gumball tried to escape his grasp, but he was to strong. To Marshall Lee's surprise, Gumball was the one to make the first move. He leaned in and kissed Marshall Lee passionately.

After a while, Marshall Lee separated the two. The both of them were very flustered. "G-gumball..." Marshall Lee was still couldn't believe he did that.

"Let's just get this over with." Gumball said. He had given in. Marshall Lee picked him up, and threw him on the bed. Marshall Lee crawled on top of him. He separated his legs, and Marshall Lee immediately started to lick at his erection. "Agh... I-I'm..." Gumball was to overwhelmed to speak correctly.

Marshall Lee was about to go from tier 8 to tier 13, but Gumball stopped him. "Did you hear that?" He looked at the door to his room. It was still slightly open. "Someone saw us. Marshall, someone saw us!" Marshall Lee didn't look concerned at all.

"Whatever. Let's keep going-"

"No! Marshall, I could dethroned! My people are very close-minded, and they would force me to go." Gumball got off the bed and locked the door.

"Can't you just make a law or something that makes them not rebel?"

"No I can't, just... leave." Gumball said. "If anyone saw us, I could just deny that this ever happened. Just please, go."

Marshall Lee felt that he needed to stay, so he came up with an idea. "But Bubs, I'm so very tired." The vampire said, obviously faking it. Marshall Lee looked at him with puppy dog eyes.

"Really?" Gumball wasn't going to fall for this... But he wanted to. He sighed. "First of all, don't call me Bubs. Second, I'm making a pillow barrier so you don't try anything."

Marshall Lee quietly whispered, "Yes!" and flopped on to one side of the bed. Gumball put pillows, and flopped down as well.

"G'night, Bubs." Marshall Lee whispered. Gumball sighed.

"Good night, Marshie."

* * *

 ** _Pew! Pew!_**

Fionna and Cake were playing a game on BMO. Fionna's character on the screen was barely moving. She looked distracted by something.

"Fionna? Is everything alright?" Cake asked her. Fionna just stared at the screen. "Fionna?" Cake waved her arm in her face.

Fionna finally snapped back. "Oh! Sorry, I'm just thinking about why Gumball left. He was gonna stay here for two more days... Do you know why?"

Cake tensed a bit. "What? Of course, I don't know..." She tried to laugh it off.

"Okay... Well, I borrow your phone for a little bit?" Fionna asked her.

"Sure! What'cha wanna do with it?" She asked.

"I'm just gonna call Gumball to see if he wants to hang."

"O-oh! Well, I think he is very busy right now, with being gone and all. I wouldn't want to bother him!" Cake didn't want to see Gumball, it would be too awkward.

"Please?" Fionna looked at her, with a slight lip quiver.

"Oh, alright. But don't bug him if he is busy." Cake handed her the phone.

 ** _Ring Ring. Ring Ring._**

"Hello?" Fionna heard Gumball's voice

"PG! Hey! It's Fionna."

"Ah, Fionna! I apologize about leaving so suddenly. I missed my people. Anyway, what was it that you wanted?"

"I was just wondering if we could hang out?"

"Definatly! It's the least I can do. How about at 8:40 in my castle?"

"I'll be there! See ya PG!" Fionna hung up the phone, and handed it back.

"So?" Cake asked, while sitting next to BMO, playing her xylophone.

"He said we could go at 8:40." Fionna said cheerfully.

"Wait, _we_? Who said I was goin'?" She crossed her arms.

"You don't want to go?" Fionna raised an eyebrow.

"Fionna, I have a date with Monochromicorn tonight. I ain't passing that up."

"Oooo~! That's so cute!" Fionna jumped up and down. "Anyway, an you at least take me to the Candy Kingdom?"

"Yeah, sure."

After a couple of hours later, Fionna was standing in front of a mirror. "Cake, Cromicorn, how do I look?" Fionna asked them.

"You're wearing the same clothes you always wear." Cake said.

Monochromicorn said something in Korean to them. "...what?" Fionna didn't understand him.

"Fionna, didn't you learn anything from that translation book I gave you?" Fionna shook her head. Cake sighed. "What he said was that you look fabulous, gurl! C'mon, let's go to Gumball's." Fionna jumped on Cake. "I'll be back soon, honey!"

Cake stretched out an open window with Fionna. They soon reached the castle. Cake looked up at the balcony connected to Gumball's room. The curtains were closed, but light bled through them. "Looks like he's waiting! Race ya?" Fionna said competitively.

"I'm already halfway there!" Cake said, stretching over Fionna and into the castle.

"Hey! That's cheating!" Fionna shouted from behind her.

Cake got to Gumball's room first, and saw a light seeping though the slightly opened door. She decided to peek in, then she regretted that decision. She saw Marshall Lee and Gumball...

Cake gasped and ran back towards Fionna. "Face Attack!" Cake said as she jumped on Fionna's face.

"Ah!" Fionna yelled. Fionna grabbed Cake and pulled her off her face. "Why did you do that?"

"Well... er..." _What should I say?_ Cake thought. "He was asleep! And, we wouldn't want to disturb him, right?"

"I guess? Well, what should I do now? I don't want to crash your date."

"Just, get on my back. I'll discuss it with him." Cake said as she stretched out.

* * *

"Let me do this, Bubs..." Marshall Lee whispered in Gumball's ear.

"I-I'm s-scared." Gumball was shaking.

"I promise to be gentle." Marshall Lee bared his teeth.

Gumball closed his eyes. "D-do it." He felt teeth sink in to his throat, feeling fluid's getting sucked out of his body...

"AHH!" Gumball screamed at the top of his lungs. He sat up and felt his throat. The scars were still there. It was about 5:00am.

He got up and sat at the edge of his bed, then ran his hand through his hair.

"Hey, Bubs. What'cha doin' up so early?" Marshall Lee said sleepily. He floated over to were Gumball was.

"Why did you come here?" Gumball asked.

Marshall Lee didn't reply.

"Tell me." Marshall Lee's face flushed. Gumball sighed. "You were hoping we'd get back together, weren't you?"

Marshall Lee looked away. "I'm sorry, but I can't go through that again, Marshall. We tried, and I felt like some sort of sex toy. I still have the scars. I still feel miserable. I just can't..."

"You can't, what? You can't _trust_ me anymore?!" Marshall Lee blurted.

"I-I... I..."

"Fine! If I'm just a problem to you, I might as well get out of your life!" Marshall Lee floated to his balcony.

"That's not what I-" Gumball was cut off by the sound of slammed doors. "...meant."

 ** _Knock Knock._**

"Is everything alright, prince?" Butterscotch asked.

"Yes, I'm fine." Gumball said, but his voice wavered. Butterscotch wasn't convinced, but left him alone.


	3. Chapter 3: Faker!

**1 Week Later...**

"Hiya!" Fionna was practicing her hatchet skills. With every 'Hiya!' Fionna shouted, Cake added a 'Woo!' at the end.

"HIYA!" Fionna put emphasis in her sound effects as she threw one at the apple on BMO's head. BMO giggled and waddled away.

"Woo! Nice throw Fionna!" Cake complimented.

"Thanks Cake. I gotta do something today." Fionna said.

"Are PG's missions for delivering daisy chains to the fluffy people not good enough anymore?"

"Well, duh! There was no fighting or adventure! Sometimes, Gumball's missions are so... boring." Fionna said slightly frustrated. She threw her other hatchet at the entry of the tree house.

"Fionna, me and the fluffy people present you with puffed pastries for-" Gumball said, walking in. He was cut off by the hatchet almost hitting hiss head, but instead only chopped part of his hair off.

"Oop! You almost chopped my crome-dome." Gumball put the pastries on a table and stretched his hair back to it's normal position.

"Whoops! Sorry PG." Fionna said.

"That's quite alright. Anyway," Gumball grabbed the puff pastries. "Me and the fluffy people made puffed pastries for you and Cake to thank you for your delivery." He offered one to her.

"Uh... Maybe later." Fionna didn't really want to eat. She just wanted adventure.

Before anything else was said, there was a big **_Whoosh!_** sound and the puff pastries were suddenly gone.

"Aw." Gumball said, disappointed. Then something thumped the roof.

"Something's on the roof!" Fionna whispered. "Let's go check it out."

"But it's wet outside." Gumball pointed out. It was raining outside.

"It is wet." Cake agreed. Fionna thought for a second.

She ended up taking Cake tucked in her hat and giving Gumball a piggy-back ride with an umbrella on her shoulders up the ladder.

When they got up to the roof, they saw Marshall Lee sucking the red out of the puff pastries Gumball had made.

"Hey, Fi." He said, seeming very pleased with himself.

"Ugh, it's you." Gumball said, angry.

"Oh, I'm sorry. Have I disappoint you, my prince?" He threw a discolored puff at him.

It splattered a bit, and stuck to Gumball's face. "Oh, honestly! Fionna, I'll be in the house if you'd like more _polite_ company." He angrily went sown the ladder, almost slipping.

"Be careful!" Fionna shouted at him.

"Heh! What a wad." Marshall Lee smirked.

"A gum-wad?" Fionna said.

Cake gasped. "Fionna!"

"Anyway, I've been hearing you are in need of an, _adventure_?" He asked.

"Ooo~! What is it?" Fionna asked enthusiastically.

"We are going to deal with those bears-"

"Bears?!" Cake jumped out of Fionna's hat, and shook her head. "M-mm! Hell no! Them bears get crazy mad when you attack them!"

"What? C'mon, Cake! Nothing bad will happen." Fionna pleaded.

"Fine, you can go. But I'm staying here." Cake stretched away into the tree house.

In the tree house, Gumball was tweaking with BMO. She went and sat next to him.

"You didn't go with them?" Gumball asked.

"Nope! They were gonna deal with bears, and I ain't doing that again." Cake shook her head.

Gumball was still focused on BMO. "I see..." After a while, Cake made a face at him. He looked at her, confused. "Why are you making that face at me?"

"I'm not making a face." Cake said, still giving him a I-know-what-you-did face. Gumball rolled his eyes. "So, when are you guys going on a date?"

"What?" Gumball didn't quite get was she was implying.

"I mean, you already probably took your relationship to tier 15, so you must be going on a date soon."

 _Oh... Marshall Lee._ He decided to pretend he didn't understand. "I have no idea what your talking about."

"Ok." She said. She knew he was lying. "Would ya want some fruit, hun?"

"Sure, as long as it's not _red_." Gumball hated the color red now.

* * *

Fionna and Marshall Lee were walking their way through a forest.

"So, were are the bears?" Fionna said excitedly. She has her sword at the ready.

"They are at..." Marshall Lee moved some bushes out of their way. "The Town of Nymphs." Behind the bush revealed a town of little houses in giant tree stumps.

"Nymphs? What are those?" Fionna asked.

"I dunno. All I know, is that they are freaking hot." Marshall Lee put his hands behind his head.

They walked for quite a while, and noticed that there weren't any Nymphs in the town. "I don't really see anything..." Fionna was kind of disappointed.

"You sure 'bout that?" Marshall Lee pointed at a bear cub.

Fionna gasped. "Oh my glob! It's so cute!" She ran over and pet it.

"Fi, I wouldn't do that of I were-"

"Ouch!" The bear cub bit her hand. Blood dripped out of the bite.

"See?"

Fionna quickly covered her wound. She looked at Marshall Lee like she was expecting him to to something. "Aren't you gonna freak out?"

"Freak out? Why?"

"Uh, this?" She held out her hand.

"Oh, blood. Yeah, I'm not really into that gunk anymore." He shrugged.

The cub that had bit Fionna's hand rolled on the ground and cried out. Bears appeared around it, then they all roared and charged at Fionna and Marshall Lee.

Marshall Lee readied his axe. "You ready?"

"Always!" Fionna and Marshall Lee attacked them.

As soon as they were killed by Fionna and Marshall Lee, they all evaporated into a black gas. "The hell?" Marshall Lee scratched his head.

"Were they supposed to disappear like that?" Fionna asked.

"I don't think so..." More bears came and surrounded them. "I think we should go and find the Nymphs." Marshall Lee suggested. He picked up Fionna and flew away.

They heard shouting from somewhere in the distance. "Maybe those are the Nymphs!" The pair floated to the place were they heard shouting. The Nymphs were all on one tower, and it was surrounded by bears.

When Fionna and Marshall Lee landed, the bears looked at them. "Nice little bears..." Fionna said, trying to stop them from attempting to attack them. They all ended up ambushing anyway, and they tried to defend themselves the best they could. Every bunch of bears killed, another wave came in.

"Ugh! They just keep coming!" Marshall Lee shouted to Fionna. Sooner or later, the bears finally lessened.

"Whew, that was a rush." Fionna was panting.

"Thank you so much! Here, have some treasure." A Nymph thanked, and brought Marshall Lee the sack full of goods.

"No prob, Bob." He threw the sack over his shoulder and floated to Fionna.

"Are you ready to go?" He asked.

"Sure... I just need... a couple more seconds." She was still panting.

"Yikes!" One of the Nymphs screamed. "There's another bear!"

"Are you kidding me?" Marshall Lee mumbled. "I'll take care of this one." Marshall Lee floated over and swung his axe at the bear. To his surprise, the bear grabbed his axe. It snatched it away from Marshall Lee, then threw the axe in a different direction.

The bear looked directly at Marshall Lee, then swung it's claws at him.

"Marshall!" Fionna yelled and ran towards them. She stabbed her sword through the bear, and it evaporated.

"Marshall! Are you okay?!" She shook Marshall, who had fallen to the ground. He coughed and looked at her, fearful.

"I... need... some help..." He managed to say.

Fionna grabbed her phone and called Cake.

"Hello?" It was Cake.

"Cake! I need your help, Marshall got hurt and I need a first-aid kit or something!"

"Ok! Were are you guys at?"

"The City of Nymphs!"

"We'll be there in a jiffy!" Cake hung up.

"C'mon, stay with me Marshall..." A few seconds later, Cake and Gumball came.

"Gumball, get the kit ready!" Cake told him.

Gumball pulled out what he thought what was a first-aid kit, but he pulled out BMO instead. "Uh... I think I have mistaken BMO for a medical kit..."

"Gumball!" Fionna and Cake shouted at him.

Marshall Lee started coughing. "Fionna, I think that this is it for me. So, admit it, your in love with me."

Fionna looked away, embarrassed. "Look, I know you act all flirty with me or whatever, but your doing this now?!" Marshall Lee looked at her, surprised. He wasn't expecting that reaction from her. "What are you trying to do to my head? You think I have some crush on you? Well, for what we have left... for once, drop it, you freak!" Tears welled up in her eyes.

"Faking it! Faking it!" Marshall Lee revealed that the bear had only slashed the pastries, not him. "Geez, Fionna. Your the one of the realist people I've ever met." He ran his hand through his hair.

"Oh, goodness." Cake and Gumball said, relieved.

Fionna punched Marshall in the face. "Ow, ma cheek meat!" Fionna started laugh-crying hysterically. "Quit clowning, Fionna. F-fionna? Fionna!" Fionna punched Marshall again.


End file.
